EP3695576B1 - Method for communicating data in an industrial network in particular, control method, device, computer program and computer-readable medium - Google Patents

Description

The invention relates to a method for data communication in a network, in particular an industrial network, in which a stream is set up between at least two stream participants, whereby at one or more nodes, in particular bridges and / or switches, located between the at least two stream participants, Resources are reserved and then data are transmitted between the at least two stream participants via the stream, as described in claim 1. The invention also relates to a control method, a device, a computer program and a computer-readable medium as described in claims 13, 14 and 15. Further forms of embodiment are described in the dependent claims.

Time Sensitive Networking (TSN) describes a series of standards that extend the bridging standard IEEE 802.1Q to include mechanisms for the transmission of real-time-critical data over Ethernet networks. The standards mentioned include, for example, time synchronization (IEEE 802.1AS-Rev), frame preemption (IEEE 802.1Qbu) and reservation (IEEE 802.1Qca, IEEE 802.1Qcc) and other standards.

With Time Sensitive Networking, a standard is defined that guarantees the quality (Quality of Service - QoS or also quality of service) in a network in the form of streams. A stream is a usually unidirectional protected communication link from a source (talker) to one or more sinks (listeners).

"Multiple Listeners per Stream" was introduced in AVB to reduce the number of real-time data flows (IEEE802 calls this "Stream") from one source (talker) to multiple destinations (listeners). Specifically, data transmission from one talker to several listeners is made possible via just one stream.

In the European patent application, which also goes back to the applicant, with the file number EP 18154319.0 a stream reservation model is also disclosed which enables "multiple talkers per listener", specifically the transmission of data from several talkers to a listener via just one stream.

In the publication of AHMED NASRALLAH ET AL: "Ultra-Low Latency (ULL), Networks: A Comprehensive Survey Covering the IEEE TSN Standard and Related ULL Research", ARXIV.ORG, CORNELL UNIVERSITY LIBRARY, 201 OLIN LIBRARY CORNELL UNIVERSITY ITHACA, NY 14853, 20. March 2018 , shows improvements for an industrial TSN network.

the US 2017/331719 A1 describes data communication by means of streams in a vehicle.

Before the actual data transmission via stream, a path calculation and a registration and reservation take place in order to obtain guarantees from the network for a loss-free, in particular real-time, transfer of data frames and punctual delivery. The network must verify the availability of network resources (e.g. address table entries, frame buffers, transmit time slices) and allocate resources - if available - for each real-time data flow, i.e. stream, and it must grant access for real-time data traffic.

Within the network, the control information on registrations, reservations and forwarding information must be stored for each stream. The status of each reservation must be maintained. With an increasing number of terminals and their data traffic, in particular real-time data traffic, in the same network, the amount of network control information increases. Since the storage and processing power of network nodes, such as brigdes or switches, is limited, this sometimes poses a scaling problem.

It can happen that one or more network participants, for example controllers, sensors and / or actuators or such comprehensive devices, are temporarily removed from the network or deactivated. This can, for example, be due to maintenance and / or a defect that needs to be repaired.

In this case, communication is temporarily no longer required because either a device that represents a talker of a stream is no longer transmitting and / or a device that is a listener of a stream can no longer receive data, so that a transmission to this is temporarily not necessary or possible. In such a case, as far as the applicant is aware, the reservation of the bandwidth on the associated network path is either retained and the bandwidth is not used otherwise, which slows down the entire network. One alternative known to the applicant is that the stream with the complete configuration is deleted, whereby the reserved resources are available again. If a temporarily removed network participant is reconnected, a completely new configuration must be carried out, and a reaction-free restart cannot be guaranteed.

Based on this, it is an object of the present invention to provide a method of the type mentioned at the beginning, which offers an optimal use of network resources, especially in the event that no data is temporarily sent to one or more stream participants and / or from this or them temporarily no data is received.

This object is achieved in a method of the type mentioned at the outset in that at least one participant in the stream interrupts the sending and / or receiving of data via the stream and resources available for the at least one participant in the stream at one or more nodes reserved for use for a data transmission that has a lower priority than data transmission via the stream, the reservation of the resources for the at least one participant being maintained, the at least one participant of the stream before or after or at the same time to the interruption of the transmission and / or reception of data via the stream sends a sleep message and, in response to the sleep message, the resources that are reserved for the at least one participant of the stream at one or more nodes for use by a Data transmission that has a lower priority than data transmission via the stream can be released.

The sleep message can be triggered, for example, from a central point and sent to the first node, in particular the first bridge, or signaled directly to the network by a network device forming a stream participant (for example a talker). The first node, in particular the first bridge, then maintains the reservation for all subsequent network components involved, although the subscriber is no longer connected to the network and / or is switched off.

A temporary interruption in data transmission to the network can be communicated in particular by sending a sleep message. The introduction of sleep messages also makes it possible in a particularly simple manner to distinguish between only temporary interruptions in sending or receiving via stream, for example due to a temporary deactivation or removal of a participant for maintenance purposes, and a permanent termination of data transmission. In the event of permanent termination, for example in the event that a device that forms a stream participant is completely removed from the network, it is not necessary to select a sleep mode in which the resource reservation is maintained, but the reservation can be dismantled again.

As an alternative or in addition to sending sleep messages, additional information about the sleep mode can also be added directly to the stream description (in particular in the reservation protocol) or through a configuration by the management of the reservation protocol. The sleep mode can then be activated in particular directly in response to an interruption in the sending and / or reception of data from a stream subscriber and / or in response to a disconnection of a stream subscriber from the network and / or a deactivation of a stream -Participant is preferably done automatically. Similarly, the sleep mode can be terminated, in particular automatically, in response to the fact that data is being sent and / or received again by the stream subscriber and / or in response to a stream subscriber being reconnected and / or connected to the network activated is switched on.

In other words, the basic idea of the present invention is to introduce a "sleep mode" for streams and, in the event that at least one stream subscriber temporarily does not want to or can not send and / or receive data, use the resources reserved for this stream To provide use for data transmission with a lower priority communication class. According to the invention, the configuration settings of the stream are retained - even during the "external use" of the resources.

The procedure according to the invention makes it possible that reserved resources are subsequently available for the stream traffic without delay when the at least one stream subscriber wants to send and / or receive data again, with the acceptance that the lower-priority communication in this Moment is disturbed. This applies in particular to network-controlled, cyclic communication, e.g. when using TAS (Time Aware Shaper).

With TAS, for example, the time slots are reserved exclusively for use by the streams. Another transmission can not use this. By pausing these can be used again. When a stream participant, for example a talker, wakes up, he can then re-initiate the reservation, but an existing scheduling is only "reactivated" and not recalculated. Another stream cannot use the resources because it is not allowed to use the scheduling. However, best effort traffic (those with "lower priority") can use the time slots in the "sleep" state until the stream registration is reactivated.

After a pause in a network participant, for example due to the removal and / or deactivation of a participant and for example in the minutes or hours range, the Resources may or may be required, data exchange can take place again. A complete recalculation of a scheduling, on the other hand, would take minutes or, in the case of more complex networks, hours.

Preferably, all resources that are reserved for the at least one stream participant who temporarily interrupts the sending and / or receiving of data are made available to the network for low-priority communication.

The released resources can be used by at least one other subscriber in the network for data transmission that has a lower priority than data transmission via the stream.

In order to maintain one or more protected connections, i.e. one or more streams, resources are reserved in a manner known per se in the node or nodes via which the data is to be transmitted before the actual transmission of the data, which is possible using a reservation protocol is.

By using a reservation protocol for the real-time flow, the complex configuration is carried out automatically in the network, using the respective topology. Resources, in particular network resources that are reserved for transmission via stream, can be address table entries and / or frame buffers and / or transmit time slices and / or bandwidth and / or jitter and / or latency, for example.

The maintenance of the reservation according to the invention following an interruption or pause in a data transmission from and / or to at least one stream participant can be achieved, for example, by using configuration data or configuration settings belonging to the reservation in one or more, preferably all, nodes which data is or is to be transmitted via the stream remain stored, even if the data transmission from or to a stream participant is temporarily suspended. The configuration data or settings that remain stored can be, for example, an address entry in the FDB, the management of the queue memory used for real-time data and / or a configuration of the shaper and / or TAS mechanism.

So far, the stream description (in particular stream ID, frame size, number of frames per interval, forwarding address used) has been updated periodically. If a link fails (for example due to the removal and / or deactivation of a talker), the values received by this device are deleted immediately.

The transmission of data via stream takes place preferably in a TSN network. A TSN network is to be understood as one which satisfies one or more standards referred to as Time Sensitive Networking (TSN), in particular comprises one or more TSN-capable nodes, such as switches and / or bridges. The TSN standards include For example, time synchronization (IEEE 802.1AS-Rev), frame preemption (IEEE 802.1Qbu) and reservation (IEEE 802.1Qca, IEEE 802.1Qcc) and other standards. In principle, it is also possible for data to be transmitted via stream in a network that (only) complies with AVB standards, in particular IEEE802.1AS, IEEE802.1Qat, IEEE802.1Qav and / or IEEE802.1BA.

According to the invention, the at least one participant in the stream can continue sending and / or receiving data via the stream using the resources reserved for him after he has interrupted the sending and / or receiving of data via the stream, whereby a any data transmission with a lower priority is terminated using the resources reserved for the at least one participant in the stream.

In particular, the at least one participant in the stream will continue to send and / or receive data via the stream without the reservation of resources for the stream being recalculated and / or carried out anew.

It may be that the at least one participant in the stream is deactivated and, in particular, due to the deactivation, no more data is sent and / or received via the stream from the at least one participant in the stream. Alternatively or additionally, it is possible that the at least one participant of the stream is disconnected from the network and, in particular, due to the disconnection from the network from the at least one participant of the stream, no more data is sent and / or received via the stream.

If the at least one participant in the stream has been disconnected from the network, it can then be reconnected to the network and the data transmission via the stream can then be continued. In the event that it has been deactivated alternatively or additionally, the at least one participant in the stream can then be reactivated and then continue data transmission over the stream. In both cases, the maintenance of the resource reservation according to the invention enables a particularly smooth and rapid resumption of the stream data transmission.

In addition, it is guaranteed that the resources are not used by another stream during the break or a "switch-off" phase and would therefore no longer be available after switching on and / or reconnecting.

It is furthermore preferably provided that the at least one participant in the stream sends a wake-up message after having interrupted the sending and / or receiving of data via the stream, and in response to the wake-up message any data transmission with a lower priority using the resources reserved for the at least one participant in the stream is terminated within a predetermined time period.

The network can be informed in a simple manner via the wake-up message that the at least one stream participant wants data transmission again.

If the interrupted data transmission from and / or to the at least one participant in the stream is due to the fact that it was disconnected from the network, it will send the wake-up message after it has been reconnected to the network, in particular immediately afterwards the reconnection.

In the same way, in the event that it was alternatively or additionally temporarily deactivated, it will send the wake-up message after it has been activated again, in particular immediately following the (re) activation.

Alternatively or additionally, it is possible that instead of the wake-up message, a regular registration of the stream previously protected by the sleep message is triggered - which then uses the previously protected resources.

Another embodiment of the method according to the invention is characterized in that the at least one participant in the stream, when sending and / or receiving data via the stream, additionally sends keep-alive messages cyclically. Then the at least one participant in the stream will preferably end the sending of keep-alive messages if he interrupts the sending and / or receiving of data via the stream. In the sleep mode provided according to the invention, the sending of keep-alive messages is appropriately suspended.

The at least one participant in the stream who temporarily interrupts the sending and receiving of data via stream is preferably a component of an industrial automation system, for example one that includes or is formed by at least one sensor and / or at least one actuator .

Of course, several participants in a network can temporarily interrupt the sending and / or receiving of data via a stream. If this is the case, the sleep mode according to the invention can only be activated for one, for several or also for all stream participants who are affected by this, in which the resources available for the respective participant in a stream at one or more nodes are reserved for use for a data transmission, which has a lower priority than the data transmission via the stream, are released, the reservation of the resources for the respective participant being maintained.

In the case of TAS, the transmission time windows can generally only be used for the stream data - by means of the invention "Sleep" mode then especially for the best effort class, for example. With other TSN shapers, the transmission of best effort can always use the bandwidth that is not required. However, a reservation of a new stream cannot use the resources required for the stream that are maintained by the "sleep" mode. Several stream participants for whom the sleep mode according to the invention is used can of course be participants in one, that is to say the same stream, as well as participants in different streams.

The present invention also relates to a control method for an industrial technical process or a vehicle, in which data is exchanged between at least two components of an automation system using the method according to one of the preceding claims and, on the basis of the exchanged data, a control of the industrial technical process or Vehicle takes place.

• einen oder mehrere Knotenpunkte, insbesondere Bridges und/oder Switches, und
• wenigstens zwei Stream-Teilnehmer bildende Geräte, die über einen oder mehrere Knotenpunkte miteinander verbunden sind, wobei die wenigstens zwei Stream-Teilnehmer bildenden Geräte bevorzugt Bestandteile einer industriellen Automatisierungsanlage sind.

Another object of the invention is a device which is designed and set up to carry out the method according to the invention for data communication or the control method according to the invention, in particular comprising:

• one or more nodes, in particular bridges and / or switches, and
• Devices forming at least two stream subscribers which are connected to one another via one or more nodes, the devices forming at least two stream subscribers preferably being part of an industrial automation system.

The invention also relates to a computer program which comprises program code means for performing the steps of the method according to the invention for data communication or the control method according to the invention.

Finally, the subject matter of the invention is a computer-readable medium which comprises instructions which, when executed on at least one computer, cause the at least one computer to carry out the steps of the method according to the invention for data communication or the control method according to the invention.

The computer-readable medium can be, for example, a CD-ROM or DVD or a USB or flash memory. It should be noted that a computer-readable medium should not be understood exclusively as a physical medium, but rather such a medium can also be present, for example, in the form of a data stream and / or a signal that represents a data stream.

FIG 1

eine schematische Teildarstellung eines industriellen Netzwerkes mit mehreren Teilnehmern, wobei zwischen zwei Netzwerk-Teilnehmern Daten über einen Stream ausgetauscht werden;

FIG 2

das Netzwerk aus FIG 1, wobei einer der beiden Netzwerk-Teilnehmer, die Daten über den Stream ausgetauscht haben, aus dem Netzwerk entfernt wurde;

FIG 3

das Netzwerk aus FIG 1 und 2, wobei der zuvor entfernet Netzwerk-Teilnehmer wieder mit dem Netzwerk verbunden ist und der Datenaustausch über den Stream fortgeführt wird;

FIG 4

eine rein schematische Darstellung zu den Abläufen bei Entfernung eines Netzwerk-Teilnehmers, wenn kein erfindungsgemäßer Sleep-Mode vorgesehen ist; und

FIG 5

eine rein schematische Darstellung zu den Abläufen bei Entfernung und anschließender erneuten Verbindung eines Netzwerk-Teilnehmers, wenn ein erfindungsgemäßer Sleep-Mode vorgesehen ist.

Further features and advantages of the present invention will become clear from the following description of an embodiment of the method of the present invention with reference to the accompanying drawings. In it is

FIG 1

a schematic partial representation of an industrial network with several participants, with data being exchanged between two network participants via a stream;

FIG 2

the network off FIG 1 , wherein one of the two network participants who exchanged data via the stream has been removed from the network;

FIG 3

the network off FIGS. 1 and 2 The previously removed network participant is reconnected to the network and the data exchange is continued via the stream;

FIG 4

a purely schematic representation of the processes when a network participant is removed if no sleep mode according to the invention is provided; and

FIG 5

a purely schematic representation of the processes involved in the removal and subsequent reconnection of a network subscriber when a sleep mode according to the invention is provided.

the FIG 1 shows a purely schematic partial representation of an industrial Ethernet-based network. Specifically, a terminal can be seen that represents a transmitter / talker 1, and that via several network nodes in the form of bridges 2, of which in the FIG 1 only four pieces are shown, is connected to a plurality of further terminals, each representing a receiver / listener 3, 4, 5. Of the recipients 3, 4, 5 are in the FIG 1 to recognize three. The three points on the right in the FIG are intended to make it clear that further bridges 2 and terminals (can) follow behind the bridge 2 at the top right.

How to get the FIG 1 As can be seen, the Ethernet-based network with the multiplicity of bridges 2 is characterized in the illustrated embodiment by a tree topology. Of course, another network topology known from the prior art, for example a line, star or ring topology, can also be provided.

In the present case, the network is a TSN network, that is to say one which meets one or more standards referred to as Time Sensitive Networking (TSN). In particular, the nodes 2 in the present case are provided by TSN-capable bridges 2. The TSN standards include, for example, time synchronization (IEEE 802.1AS-Rev), frame preemption (IEEE 802.1Qbu) and reservation (IEEE 802.1Qca, IEEE 802.1Qcc) and other standards.

In the present case, the terminal device forming the transmitter is a PLC 1 of an industrial automation system for a technical process not shown further. The terminals forming the receivers are a screen 3 on which data received from the PLC 1 is visualized for an operator can be, a terminal 4, which comprises one or more actuators not recognizable in the figures, which cyclically require control signals from the PLC 1 in order to have a cyclical effect on the industrial technical process, and an analysis device 5, which receives data from the PLC 1 and this analyzed. The industrial technical process is controlled on the basis of the data exchanged between the PLC 1 and the device 4.

The data are transmitted from the PLC 1 to the three terminals 3, 4, 5 in the form of data frames via the Ethernet-based network.

The frame forwarding from the PLC 1 to the device 4 with the actuators takes place via a protected connection, a so-called stream. The data communication via a stream, which is known for example from the AVB and TSN standard (TSN stands for "Time Sensitive Networking"), ensures in particular that a predetermined latency, which can vary from stream to stream, and in particular from the depends on the application. This ensures that the control signals arrive at the actuators of the terminal 4 within a predetermined maximum latency period, i.e. a maximum latency period passes between the data being fed into the network by the PLC 1 and the data being received by the actuators. For example, a particularly real-time critical communication between the PLC 1 and the device 4 with the actuators can be ensured.

The rule here is that a stream, as defined, for example, by the Audio / Video Bridging (AVB) task group and in particular by the TSN task group in the international standard IEE802.1, makes use of a stream reservation protocol (in this case, for example, Stream Reservation Protocol - SRP or the extension MSRP) is set up, whereby a stream between a sender and a receiver or a stream between a sender 1 and several receivers can be obtained. The former configuration clearly corresponds to the one from FIG 1 .

To set up a stream between the PLC 1 and the device 4, resources are reserved at each node 2, which forwards data frames from the PLC 1 to the device 4.

The sequence is such that in a first step the sender, that is to say the PLC 1, issues a Talker Advertise message. The PLC 1 uses this to announce the stream in the network, and the properties of the stream are described. The PLC 1 specifies, in particular, a stream ID, a forwarding address and bandwidth information for the data transfer outgoing from it.

The announcement of the stream is distributed to all nodes, in this case bridges 2 in the network, with each bridge 2 then receiving the information from the receiving port, i.e. the port in the direction of the PLC 1 forming the talker via which the announcement was received, and later also the Data will come in, leads. Since the data source is also called Talker 1, this port is also called Talker Port. The ports in the direction of the listener (s) are accordingly also referred to as send or listener ports.

One or more listeners can log on to the stream offered by the PLC 1. In the exemplary embodiment shown, only the device 4 logs on with the actuators, although this is not to be understood as restrictive and it is of course also possible for several listeners to log on. A listener join message is sent from the device 4 in the direction of the PLC 1.

At those bridges 2 that are between the PLC 1 and the device 4, a reservation is made at the port in the direction of the device 4, i.e. the listener port according to the stream description given by the PLC 1 representing the talker carried out, provided that the available resources at the respective bridge 2 are sufficient. Each node 2 checks whether its internal resources are sufficient for the performance required in the context of the stream to be set up (in particular with regard to data volume and data throughput). If this is the case, node 2 reserves these resources for the stream to be set up and forwards a positive reservation status to the following bridge 2, or the last bridge to the sender, i.e. the PLC 1. In the exemplary embodiment shown, the PLCs are located on this 1 with the device 4 connecting network path a total of three nodes, here bridges 2 and resource reservations are made at these three.

Each node 2 can use the reservation to ensure that it guarantees the required performance during the subsequent data transfer. This is where streams differ from unprotected connections.

If insufficient resources are available, a negative reservation status is passed on.

The reservation starts at the bridge 2 closest to the respective receiver / listener, ie the device 4, and "propagates" along the associated network path to the data source / to the talker, ie the PLC 1.

The reservation is based on the forwarding tree, also known as the talker tree (T _Tree ), which can be set up, for example, with the Rapid Spanning Tree Protocol (RSTP).

Following a successful reservation, data frames are transmitted cyclically from the PLC 1 to the device 4. The device 4 sends "keep-alive messages" to the next node 2 on the network path from the device 4 to the PLC 1. This maintains the reservation. After the timer expires, unconfirmed reservations are flagged and internally deleted after a confirmation time (2nd timer) has elapsed. This means that devices that were previously removed are recognized, the reservation is cleared and the resources are released again.

Data frames are also sent cyclically from the PLC 1 to the two other devices 3, 5, but, since they do not need the data in real time, not via a protected connection, i.e. not via stream. No resources are therefore reserved at the nodes 2 on the network path between the respective device 3, 5 and the PLC 1 for data transmission to the two further devices 3, 5.

In the FIG 1 an arrow 6 connecting the PLC 1 to the device 4 with the actuators schematically indicates that the data is transmitted via stream.

In the FIG 4 a device or trigger is indicated purely schematically and by way of example by a bar marked with the reference number 7 and an associated network path (which is defined by one or more nodes 2) by an opposite bar marked with the reference number 8. An arrow 9 pointing from the device or trigger 7 to the network path 8 indicates the command to reserve resources for setting up a stream. Another arrow 10 from the device or trigger 7 to the network path 8 symbolizes the data communication using the reserved stream 6.

It can happen that one or more network participants are temporarily removed from the network and / or deactivated. This can, for example, be due to maintenance and / or a defect that needs to be repaired.

In this case, communication is temporarily no longer required because either the device is no longer sending and / or no longer receiving data. In the present case, no more data is taken from the device 4.

In the event that a remote or deactivated device represents a stream participant and the resource reservation is maintained on the associated network path, the bandwidth cannot be used otherwise when using TAS and an exclusive time window for the stream slowing down the entire network. If the stream were deleted, however, the reserved resources would be available again. As soon as the only temporarily removed or deactivated network participant is reconnected or activated, however, a completely new configuration would have to take place, and a reaction-free restart cannot be guaranteed.

In the FIG 2 is - purely schematically - the separation of the device 4 from the network is illustrated by an arrow 1.

In the FIG 4 is indicated by a third, deflected arrow 12 and a cross 13 that no more data is sent and / or received from the temporarily removed and / or deactivated device.

In order to enable optimal use of network resources in particular in the event that no data is temporarily sent to one or more stream participants and / or no data is (can) be received from this or them temporarily, a sleep mode is provided according to the invention.

Specifically, the device 4 forming a stream participant interrupts the sending and / or receiving of data via the stream 6, the resources that are required for the device 4 at all nodes, in this case bridges 2, on the network path between the PLC 1 and the Device 4 reserved are released for use for data transmission that has a lower priority than data transmission via stream 6.

The reservation of the resources for the device 4 at the three nodes 2 between the PLC 1 and the device 4 remains - despite the release for the low-priority use and during any use of the resources for a low-priority communication. The reservation will not be canceled. Specifically, configuration settings belonging to the reservation remain stored at all three nodes 2, in this case the address entry in the FDB, the management of the queue memory used for real-time data and the necessary configuration of the shaper or the TAS mechanism. When using IEEE 802.1 CB, the filters required to identify the stream data and the history required to identify duplicates for storing the previously received sequence numbers must also be available in the bridges.

To activate the sleep mode, the device 4 can send the sleep property of a stream to the next node 2 directly in an extended stream description, send as a notification in an extended stream description, as a notification in a sleep mode message, or send it the setting for the stream can be made from a central point in the management of network component 2 or a message can be sent to bridge 2.

In the FIG 5 this is indicated - again in a purely schematic manner - specifically the sending of the sleep message to the next node 2 on the network path 8 between PLC 1 and device 4 by an arrow 14, which points from the one on the left in the FIG. a bar 7 representing a trigger points to the bar 8 representing the network path. In the sleep mode, which is indicated by a block element provided with the reference number 15, the resources are made available for lower-priority use, while the reservation is retained.

In the exemplary embodiment shown, the released resources at the three nodes 2 on the network path 8 are used to transfer data from the PLC 1 to the screen 3 and the analysis device 5, the latter only using the resources of two of the three nodes 2 due to the path geometry uses, the screen 3, however, from all three nodes 2 (cf. Figures 1 to 3 ).

After maintenance of the remote device 4 has been completed, for example, the device 4 is reconnected to the network, which is shown schematically in FIG FIG 3 is indicated therein by an arrow 16.

As soon as the device 4 is reconnected to the network, it sends a wake-up message to the three nodes 2 on the network path 8, which connects the PLC 1 to the device 4.

The sending of the wake-up message is in the FIG 5 indicated by an arrow 17 from the bar 7 to the bar 8. In response to the wake-up message, any data transmission with a lower priority is terminated using the resources reserved for the at least one participant in the stream, and the participants are signaled that the reservation is active again. The resources made available beforehand ensure that the reservation made previously has enough resources available again in the nodes 2.

The device 4 then continues to receive data from the PLC 1 via the stream 6 without the reservation of resources for the stream 6 being recalculated and / or carried out anew. The reservations maintained according to the invention during the sleep mode at the three nodes 2 are thus available again almost immediately, in particular after only one or a few ms.

The restoration of data communication is in the FIG 5 represented by an arrow 18, which of which the sleep mode representing block element 15 to the network path.

It should be noted that the Figures 1 to 3 illustrated components can represent part of an embodiment of a device according to the invention, which then in turn forms part of an automation system.

The procedure according to the invention enables resources that are temporarily not required and reserved for a stream to be used elsewhere, so that optimal use of existing network resources can take place, with the resources being guaranteed without delay at the same time following a temporary non-use of a stream are available again for stream traffic. This is based on the acceptance that the lower-priority communication may be disturbed at this moment.

Although the invention has been illustrated and described in more detail by the preferred exemplary embodiment, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

For example, it goes without saying that even if the sleep mode according to the invention was described in the context of the above exemplary embodiment for a stream 6 with two stream participants 1, 4, this is for the case that two or more streams are set up in a network a stream participant temporarily does not send and / or receive data via the stream, can be activated for two or more streams.

The sleep mode according to the invention can of course also be used if a participant temporarily does not transmit from a stream with more than two stream participants and / or receives or several participants temporarily do not send and / or receive.

Finally, it must be clear that the at least two stream subscribers given by a PLC 1 and a device 4 with actuators within the scope of the exemplary embodiment described above are only selected as examples, and stream subscribers for whom a sleep mode is set up according to the present invention , can also be in the form of any other devices.

Claims (15)

1. Method for data communication in a TSN network, wherein a stream (6) is established between at least two stream subscribers (1, 4), wherein resources are reserved at one or more node points between the at least two stream subscribers (1, 4) and subsequently data is transmitted between the at least two stream subscribers (1, 4) via the stream (6), wherein at least one subscriber (4) of the stream (6) interrupts the transmission and/or reception of data via the stream (6) and resources that are reserved at one or more node points (2) for the at least one subscriber (4) of the stream (6) are released for use for a data transfer that is given a lower priority than the data transfer via the stream (6), wherein the reservation of the resources is maintained for the at least one subscriber (4),
   characterised in that
   the at least one subscriber (4) of the stream (6) transmits a sleep message (14) before or after or simultaneously with the interruption of the transmission and/or reception of data via the stream (6) and, in reaction to the sleep message (14), the resources that are reserved at one or more node points (2) for the at least one subscriber (4) of the stream (6) are released for use for a data transfer that is given a lower priority than the data transfer via the stream (6).
2. Method according to claim 1,
   characterised in that
   the at least one subscriber (4) of the stream (6), after it has interrupted the transmission and/or reception of data via the stream, subsequently continues the transmission and/or reception of data via the stream using the resources reserved for it, wherein any data transfer with a lower priority using the resources reserved for the at least one subscriber of the stream is ended.
3. Method according to claim 2,
   characterised in that
   the at least one subscriber (4) of the stream (1) continues the transmission and/or reception of data via the stream (6) without the reservation of resources for the stream (6) being calculated and/or carried out anew.
4. Method according to one of the preceding claims,
   characterised in that
   the released resources are used by at least one further subscriber (3, 5) of the network for a data transfer which is given a lower priority than the data transfer via the stream.
5. Method according to one of the preceding claims,
   characterised in that
   the at least one subscriber (4) of the stream (6) is deactivated and, in particular due to the deactivation of the at least one subscriber (4) of the stream (6), no more data is transmitted and/or received via the stream (6), and/or the at least one subscriber (4) of the stream (6) is separated from the network and, in particular, due to the separation from the network of the at least one subscriber (4) of the stream (6), no more data is transmitted and/or received via the stream (6) .
6. Method according to claim 5,
   characterised in that
   the at least one subscriber (4) of the stream (6) has been separated from the network and thereafter is reconnected to the network, and/or in that the at least one subscriber (4) of the stream (6) has then been deactivated and thereafter is reactivated.
7. Method according to one of the preceding claims,
   characterised in that
   the at least one subscriber (4) of the stream (6), after it has interrupted the transmission and/or reception of data via the stream (6), transmits a wake-up message (17) and, in reaction to the wake-up message (17), any data transfer with a lower priority using the resources reserved for the at least one subscriber (4) of the stream (6) is ended within a predetermined timespan.
8. Method according to claim 6 and 7,
   characterised in that
   the at least one subscriber (4) of the stream (6) transmits the wake-up message (17) after it has been reconnected to the network, and/or in that the at least one subscriber (4) of the stream (6) transmits the wake-up message (17) after it has been reactivated.
9. Method according to one of the preceding claims,
   characterised in that
   the at least one subscriber (4) of the stream (6), if it transmits and/or receives data via the stream (6) additionally transmits keep-alive messages, and the at least one subscriber (4) of the stream (6), in particular, ends the transmission of keep-alive messages when it interrupts the transmission and/or reception of data via the stream (6).
10. Method according to one of the preceding claims,
    characterised in that
    the reservation of the resources for the at least one subscriber (4) of the stream (6) is maintained in that configuration data and/or configuration settings belonging to the reservation remain stored at one or more node points (2).
11. Method according to one of the preceding claims,
    characterised in that
    the at least one subscriber (4) of the stream (6) is a component of an industrial automation system which preferably comprises at least one sensor and/or at least one actuator or is formed thereby.
12. Control method for an industrial technical process or a vehicle, wherein data is exchanged between at least two components (1, 4) of an automation system while carrying out the method according to one of the preceding claims and, on the basis of the exchanged data, control of the industrial technical process or vehicle takes place.
13. Device designed and configured for carrying out the method according to one of claims 1 to 12, comprising:

    - one or more node points,

    - at least two devices (1, 4) forming stream subscribers which are connected to one another by means of one or more node points (2), wherein the devices (1, 4) forming at least two stream subscribers are preferably components of an industrial automation system.
14. Computer program comprising program code means which, when they are carried out on at least one computer, cause the at least one computer to carry out the method according to one of claims 1 to 12.
15. Computer-readable medium which comprises instructions which, when they are carried out on at least one computer, cause the at least one computer to carry out the steps of the method according to one of claims 1 to 12.

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